20SEH cam swap !

The Setup: The GM/Opel/Vauxhall SOHC 8 valve Family 2 engine is not popular in the US by any stretch of the imagination (except for possibly a handful of turbo LT3/C20GET fans,) particularly when it comes to modifications and upgrades, which means they’re pretty hard to find. In other parts of the world however, it does have a small following and is even still produced. The port injected US “LE4” is roughly equivalent to the European C20NE, but Europe got something the US did not: the 20SEH – which was essentially a C20NE with higher compression (from different pistons) and a hotter cam… The result was 130hp as opposed to the LE4’s 110. So taking into account the couple horsepower lost from the compression drop, the cam has the potential to add some power.

I was previously running a factory replacement Sealed Power CS838 cam (so any reference to the stock cam is to it.) The 20SEH has the same amount of lift, but more duration. I can’t find the duration for the CS838, but the 20SEH supposedly has 264 advertised duration (unconfirmed.) The duration difference was visible on the profile from cam to cam though. I didn’t degree it yet, and just installed it aligned with the marks along with my new adjustable cam pulley. Also, no tuning was done, so it’s still all factory computer, fuel pressure, etc. That could mean either it’s fine as is which would not be a bad thing, or there could be some room for improvement by setting it up properly.

First impressions on the 20SEH cam: It idles like stock and performs very similar to stock below 3k rpm.  Any difference is not very noticeable in this range. The powerband seems broader and higher, pulling considerably stronger from above 3k all the way up to 6k where stock flattened off much sooner. It does not feel like it adds much torque overall but maybe some up higher where the power gain is realized. All in all I think it was a very worthwhile swap and seems great for a daily driven street car, giving it a little extra something and the computer seems happy enough with it. To anyone thinking of trying it out, I’d say don’t expect miracles from the swap, but considering the fact that few modifications exist at all for this engine, let alone inexpensive (about $125 shipped) and relatively easy ones like this, it’s worth it.  I’m interested to see what playing with cam timing and eventually some tuning will do for it.

Swap notes: It took me a fair amount of research, time, and reading to figure out if this would even work, like if the cam carrier diameters were different between US and European models, other differences, if they were available at all, how to get one to the US, and so on.  So where can you get a 20SEH cam you ask? The secret is if you simply put “1990 vauxhall cavalier 2.0l l4 sohc” into rockauto, they carry two different brands of 20SEH cam and will ship them right to your door from the UK. The first is the AE CAM429 which is what I went with and the second is the BGA CS5336 (add K for rockers and FK for rockers and lifters for around $280 shipped.) Obviously you should put in new followers/rockers when you swap, but it may be cheaper to get some locally. Another secret is if you can find the SBI 180-1028 followers, they are forged and higher quality than most of the standard ones. I have a set for my aftermarket cam that I’m saving for a rebuild, but just put in some generic ones for this swap. A couple more things to note are, I don’t think the 20SEH cam is machined to accept a distributor, so if you are using one, it would have to be modified. Also I had a  minor problem with my rocker removal tool, so I’ll be doing a new post soon with an improved version. The short version is, it was kicking a lash cap off the valve due to not being able to stay perfectly straight. It was only a problem on the last follower for some reason.

Other stuff: The other thing I did at the same time is finished up and installed my adjustable two piece vernier pulley, after the demise of the one piece one. A while ago, I also replaced my fuel feed line when it started leaking with nylon line and AN fittings using some adapters I designed and made. I may do a post dedicated to what’s involved with all that once I do the return side. I also attended a large cruise/car show within a few hours of finishing up the cam swap, which was pretty fun. It was mostly classics, hot rods, and muscle cars, and someone said to me that they liked my car and it was very different, but “this sort of thing isn’t really ‘accepted’ here.” Not in a negative way, just that it’s not the norm. It was funny. I need to make a post of all the random comments I get about the car one day. That is all for now, hope it’s been informative!

Edits: random addition; I believe I’m the only person in the states who has done this particular cam swap before as far as I’ve been able to tell…
Also forgot to mention that I have been running 93 octane before and after the swap to be on the safe side.